This invention relates generally to electronic musical instruments, and more particularly to an electronic piano circuit arrangement which combines a plurality of different signals to obtain the desired tone quality to a piano note. More specifically, the invention is directed to a circuit arrangement which enables combining a multitude of different frequencies in a simple and efficient manner to obtain the desired piano note quality characteristics.
Heretofore, the reproduction of piano sounds by electronic means has been, at best, a first order approximation of the frequency and its associated harmonics. Through extensive research over the years it has been discovered that the actual quality of a piano note, as perceived by listeners, is a combination of factors such as the fundamental frequency, the attack characteristic, the decay characteristic, the harmonics and the combination of other unrelated frequencies. By experimentation it has been determined that by adding the proper amplitudes of harmonics and other frequencies to the fundamental frequency, a more accurate electronic reproduction of an actual piano note can be made. By varying the amplitude of the various signals to be combined, one can produce a piano note quality which is virtually undetectable from that of a real piano tone. This information was set forth in The Journal of the Acoustical Society of America, Volume 34, Number 6, in June of 1962.
In the past, the production of such high quality electronic piano tones has been a very expensive and difficult procedure in that it required large numbers of oscillators and variable amplitude control circuits to insure the proper combination of amplitude signals. This prior art approach was very impractical and required enormous expense and time to produce a piano of the electronic type having the desired tone quality characteristics.